Nuclear Theory·nucl-th

Thursday·December 27, 2018

22 papers—12 primary·10 cross-listed

01
Parton distribution functions from scalar light-front parton gas model
Shaoyang Jia🇺🇸 · James P. Vary🇺🇸
We propose an application of a microcanonical ensemble with light-front kinematics to model the phase-space distribution of relativistic constituents of a bound state. These constituents denoted by partons are treated as classical spin-zero particles confined inside the bound state with inter-parton collisions as their only interaction. The microcanonical molecular dynamics ensemble is applied to obtain the phase-space distribution of such a thermodynamic system. We sample this phase-space distribution using Monte Carlo algorithms to obtain the parton distribution functions (PDFs) in scenarios with $3$ , $4$ , and $5$ identical partons. In addition PDFs when a selected number of massless partons are mixed with $3$ massive partons are also presented.
nucl-thPhysica A(2025)·6 citations
02
A realistic spectral function model for charged-current quasielastic-like neutrino and antineutrino cross sections on $^{12}$ C
M.V. Ivanov🇧🇬 · A.N. Antonov🇧🇬 · G.D. Megias🇪🇸 · J.A. Caballero🇪🇸 · M.B. Barbaro🇮🇹 · J.E. Amaro🇪🇸 · I. Ruiz Simo🇪🇸 · T.W. Donnelly🇺🇸 · J.M. Udias🇪🇸
A detailed study of charged current quasielastic neutrino and antineutrino scattering cross sections on a $^{12}$ C target with no pions in the final state is presented. The initial nucleus is described by means of a realistic spectral function $S (p, E)$ in which nucleon-nucleon correlations are implemented by using natural orbitals through the Jastrow method. The roles played by these correlations and by final-state interactions are analyzed and discussed. The model also includes the contribution of weak two-body currents in the two-particle two-hole sector, evaluated within a fully relativistic Fermi gas. The theoretical predictions are compared with a large set of experimental data for double-differential, single-differential and total integrated cross sections measured by the MiniBooNE, MINER $ν$ A and T2K experiments. Good agreement with experimental data is found over the whole range of neutrino energies. The results are also in global good agreement with the predictions of the superscaling approach, which is based on the analysis of electron-nucleus scattering data, with only a few differences seen at specific kinematics.
nucl-thPRC(2019)·26 citations
03
Asymmetric Nuclear Light Clusters In Supernova Matter
Andrey Yudin · Matthias Hempel · Sergei Blinnikov · Dmitriy Nadyozhin · Igor Panov
We explore the appearance of light clusters at high densities of collapsing stellar cores. Special attention is paid to the unstable isotope H4, which was not included in previous studies. The importance of light clusters in the calculation of rates for neutrino matter interaction is discussed. The main conclusion is that thermodynamic quantities are only weakly sensitive to the chemical composition. The change in pressure and hence the direct change in collapse dynamics will be minor. But the change in neutrino heating and neutronization processes can be significant.
nucl-thastro-ph.HEastro-ph.SRMNRAS(2019)·13 citations
04
How to produce new superheavy nuclei?
K. Siwek-Wilczyńska🇵🇱 · T. Cap🇵🇱 · M. Kowal🇵🇱
Existing experimental facilities limit the possibilities for discovery of new nuclides to those synthesized with cross sections above 100 fb, but the perspectives for future high current accelerators could lower this limit by two orders of magnitude. Therefore, in the present work excitation functions for fusion- $x n$ evaporation reaction channels induced not only by $^{48} C a$ but also by heavier projectiles (usually leading to smaller cross sections) on actinide targets were calculated in the framework of the fusion-by-diffusion (FBD) model. For the first time, in this approach, channels in which a proton ( $p x n$ ) or alpha particle ( $α$ $x n$ ) is evaporated have been included in the first step of the deexcitation cascade. To calculate the synthesis cross sections entry data such as fission barriers, ground-state masses, deformations and shell effects of the superheavy nuclei calculated in a consistent way within the Warsaw macroscopic-microscopic model were used. The only adjustable parameter of the FBD model is the injection point distance $s_{inj}$ and the value determined in our previous analysis of experimental cross sections for the synthesis of superheavy nuclei of Z=114-118 has been used. Excitation functions for the synthesis of selected (cross section above a few fb) new superheavies in the range of atomic numbers 112-120 are presented. Observation of 21 new heaviest isotopes is predicted. A realistic discussion of the FBD model uncertainties is presented for the first time.
nucl-thPRC(2019)·31 citations
05
Pairing in Nuclear Matter and Finite Nuclei
Herbert Müther · Artur Polls
Effects of pairing with isospin $T = 0$ and $T = 1$ are systematically studied in a model, which is based on a realistic nucleon-nucleon interaction and allows to describe the transition from infinite nuclear matter to finite nuclei. Special attention is paid to the development of the spin-orbit term in the mean field of nucleons in finite nuclei. The spin-orbit term yields a drastic suppression of $T = 0$ proton-neutron pairing but does not lead to a complete disappearance in finite nuclei. Arguments are presented, why no clear evidence of $T = 0$ pairing can be observed in the binding energies of finite nuclei.
nucl-thPRC(2019)·9 citations
06
Impact of the neutron star crust on the tidal polarizability
J. Piekarewicz · F.J. Fattoyev
The first detection of a binary neutron star merger has opened the brand new era of multimessenger astronomy. This historic detection has been instrumental in providing constraints on the tidal polarizability of neutron stars. In turn, the tidal polarizability has been used to impose limits on stellar radii and ultimately on the equation of state (EOS). The tidal polarizability is also sensitive to the second tidal Love number k2. It is the main purpose of this work to perform a detailed study of k2 which, for a given compactness parameter, encodes the entire sensitivity of the tidal polarizability to the EOS. In particular, we examine the role that the crustal component of the EOS plays in the determination of k2. A set of realistic models of the equation of state that yield an accurate description of the properties of finite nuclei and support neutron stars of two solar masses is used. Given that the tidal polarizability scales as the fifth power of the compactness parameter, a universal relation exists among the tidal polarizability and the compactness parameter that is highly insensitive to the underlying EOS. Thus, besides an extraction of the tidal polarizabilities, a measurement of the individual stellar masses is also required to impact the mass-radius relation. However, we observe a strong sensitivity of k2 to the EOS, particularly to the contribution from the inner crust. Although by itself the tidal polarizability can not contribute to the determination of the mass-radius relation, future detections of binary neutron star mergers are poised to provide significant constraints on both the tidal polarizabilities and masses of the individual stars, and thus ultimately on the mass-radius relation. Yet, subleading corrections to the tidal polarizability are encoded in the second Love number k2 which displays a large sensitivity to the entire (crust-plus-core) EOS.
nucl-thastro-ph.HEnucl-exPRC(2019)·68 citations
07
Role of fluctuations on the pairing properties of nuclei in the random spacing model
M. A. A. Mamun · C. Constantinou · M. Prakash
The influence of thermal fluctuations on fermion pairing is investigated using a semiclassical treatment of fluctuations. When the average pairing gaps along with those differing by one standard deviation are used, the characteristic discontinuity of the specific heat at the critical temperature $T_{c}$ in the BCS formalism with its most probable gap becomes smooth. This indicates the suppression of a second order phase transition as experimentally observed in nano-particles and several nuclei. Illustrative calculations using the constant spacing model and the recently introduced random spacing model are presented.
nucl-thSpringer Proc.Phys.(2020)·0 citations
08
Fusion barrier distribution and superheavy elements
K. Hagino · T. Tanaka
The barrier distribution, originated from channel coupling effects in heavy-ion fusion reactions, has been extracted experimentally for many systems using either a fusion excitation function or an excitation function of large-angle quasi-elastic scattering. In this article, we discuss an application of the latter method to the $^{48}$ Ca+ $^{248}$ Cm system, which is relevant to hot fusion reactions to synthesize superheavy elements. To this end, we carry out coupled-channels calculations for this system, taking into account the deformation of the target nucleus, and discuss the role of deformation in a formation of evaporation residues.
nucl-thnucl-exJ.Phys.Conf.Ser.(2019)·3 citations
09
Nuclear modification of full jets and jet structure in relativistic nuclear collisions
Ning-Bo Chang🇨🇳 · Guang-You Qin🇨🇳 · Yasuki Tachibana🇺🇸
With our coupled jet-fluid model, we study the nuclear modifications of full jets and jet structures for single inclusive jet and $γ$ -jet events in relativistic heavy-ion collisions. The evolution of full jet showers is studied via a set of coupled transport equations including the effects of collisional energy loss, transverse momentum broadening and medium-induced splitting. The dynamics of the jet energy and momentum deposited into the medium is described by hydrodynamic equations with source terms. Our detailed analysis indicates that collisional absorption (energy loss) tends to narrow the jet shape function while transverse momentum kicks and medium-induced radiations broaden the jet transverse profile. Also, jet-induced flow plays a significant contribution to jet shape function and dominates at large angles away from the jet axis. The final nuclear modification pattern for the jet shape function is a combined effect from various jet-medium interaction mechanisms. Our detailed studies for single inclusive jets and $γ$ -jets for various kinematics indicate that the nuclear modification of jet shape has strong dependence on jet energy and collision energy, and weak dependence on jet flavor (quark or gluon).
nucl-thnucl-exPoS(2018)·0 citations
10
Spectroscopy of odd-odd nuclei within the interacting boson-fermion-fermion model based on the Gogny energy density functional
K. Nomura · R. Rodríguez-Guzmán · L. M. Robledo
We present a method to calculate spectroscopic properties of odd-odd nuclei within the framework of the Interacting Boson-Fermion-Fermion Model based on the Gogny energy density functional. The $(β, γ)$ -deformation energy surface of the even-even (boson-)core nucleus, spherical single-particle energies and occupation probabilities of the odd neutron and odd proton, are provided by the constrained self-consistent mean-field calculation within the Hartree-Fock-Bogoliubov method with the Gogny-D1M functional. These quantities are used as a microscopic input to fix most of the parameters of the IBFFM Hamiltonian. Only a few coupling constants for the boson-fermion Hamiltonian and the residual neutron-proton interaction are specifically adjusted to reproduce experimental low-energy spectra in odd-mass and odd-odd nuclei, respectively. In this way, the number of free parameters involved in the IBFFM framework is reduced significantly. The method is successfully applied to the description of the low-energy spectra and electromagnetic transition rates in the odd-odd $^{194, 196, 198}$ Au nuclei.
nucl-thnucl-exPRC(2019)·17 citations
11
Hadron modification in a dense baryonic matter
G. Musulmanbekov🇷🇺
Starting with the Strongly Correlated Quark Model of a hadron structure, SCQM, we demonstrate how the properties of mesons and baryons are modified in a hot and dense nuclear environment. These in-medium modifications can lead to the observable effects in heavy ion collisions, such as enhancement of strangeness and dropping vector meson masses.
nucl-thEPJ Web Conf.(2019)·1 citation
12
Zemach moments and radii of 2,3H and 3,4He
N. Nevo Dinur · O.J. Hernandez · S. Bacca · N. Barnea · C. Ji · S. Pastore · M. Piarulli · R. B. Wiringa
We present benchmark calculations of Zemach moments and radii of 2,3H and 3,4He using various few-body methods. Zemach moments are required to interpret muonic atom data measured by the CREMA collaboration at the Paul Scherrer Institute. Conversely, radii extracted from spectroscopic measurements can be compared with ab initio computations, posing stringent constraints on the nuclear model. For a given few-body method, different numerical procedures can be applied to compute these quantities. A detailed analysis of the numerical uncertainties entering the total theoretical error is presented. Uncertainties from the few-body method and the calculational procedure are found to be smaller than the dependencies on the dynamical modeling and the single nucleon inputs, which are found to be <= 2%. When relativistic corrections and two-body currents are accounted for, the calculated moments and radii are in very good agreement with the available experimental data.
nucl-thPRC(2019)·34 citations
13
Baryonic susceptibilities, quark-diquark models, and quark-hadron duality at finite temperature
E. Megias🇪🇸 · E. Ruiz Arriola🇪🇸 · L.L. Salcedo🇪🇸
Fluctuations of conserved charges such as baryon number, electric charge and strangeness may provide a test for completeness of states in lattice QCD for three light flavors. We elaborate on the idea that the corresponding susceptibilities can be saturated with excited baryonic states with an underlying quark-diquark structure with a linearly confining interaction. Using Polyakov-loop correlators we show that in the static limit, the quark-diquark potential coincides with the quark-antiquark potential in marked agreement with recent lattice studies. We thus study in a quark-diquark model the baryonic fluctuations of electric charge, baryon number and strangeness: $χ_{B Q}$ , $χ_{B B}$ and $χ_{B S}$ ; by considering a realization of the hadron resonance gas model in the light flavor sector of QCD. These results have been obtained by using the baryon spectrum computed within a relativistic quark-diquark model, leading to an overall good agreement with the spectrum obtained with other quark models and with lattice data for the fluctuations.
↳ hep-phhep-latnucl-thPRD(2019)·4 citations
14
Role of the spectator system in electromagnetic effects
K. Mazurek🇵🇱 · A. Rybicki🇵🇱 · A. Szczurek🇵🇱 · V. Ozvenchuk🇵🇱 · P.N. Nadtochy🇷🇺 · A. Kelic🇩🇪 · A. Marcinek🇵🇱
The electromagnetic effects on charged pion ( $π^{+}, π^{-}$ ) spectra provide new, independent information on the space-time evolution of the ultrarelativistic heavy ion collision. The spectator life time and its excitation energy may also be of importance for the understanding of the space-time evolution of the participant zone. This paper gives an overview of our coordinated effort to understand the interplay between electromagnetic phenomena and processes related to the fragmentation of the spectator system at forward rapidity in peripheral $P b$ + $P b$ collisions at top CERN SPS energies. Our study includes on one hand the experimental analysis of electromagnetic effects and corresponding phenomenological Monte Carlo simulations, and on the other hand dedicated theoretical calculations based on the Abrasion-Ablation model ABRABLA and the 4D Langevin approach.
↳ hep-phnucl-th0 citations
15
Tri-meson bound state $B B B^{*}$ via delocalized $π$ ~Bond
Li Ma🇩🇪 · Qian Wang🇩🇪 · Ulf-G. Meißner🇩🇪
During the last decades, numerous exotic states which cannot be explained by the conventional quark model have been observed in experiment. Some of them can be understood as two-body hadronic molecules, such as the famous $X (3872)$ , analogous to deuteron in nuclear physics. Along the same line, the existence of the triton leaves an open question whether there is a bound state formed by three hadrons. Since, for a given potential, a system with large reduced masses is more easier to form a bound state, we study the $B B B^{*}$ system with the one-pion exchange potential as an exploratory step by solving the three-body Schrödinger Equation. We predict that a tri-meson molecular state for the $B B B^{*}$ system is probably existent as long as the molecular states of its two-body subsystem $B B^{*}$ exist.
↳ hep-phnucl-thPRD(2019)·13 citations
16
Comparing treatments of weak reactions with nuclei in simulations of core-collapse supernovae
Hiroki Nagakura🇺🇸 · Shun Furusawa🇯🇵 · Hajime Togashi🇯🇵 · Sherwood Richers🇺🇸 · Kohsuke Sumiyoshi🇯🇵 · Shoichi Yamada🇯🇵
We perform an extensive study of the influence of nuclear weak interactions on core-collapse supernovae (CCSNe), paying particular attention to consistency between nuclear abundances in the equation of state (EOS) and nuclear weak interactions. We compute properties of uniform matter based on the variational method. For inhomogeneous nuclear matter, we take a full ensemble of nuclei into account with various finite-density and thermal effects and directly use the nuclear abundances to compute nuclear weak interaction rates. To quantify the impact of a consistent treatment of nuclear abundances on CCSN dynamics, we carry out spherically symmetric CCSN simulations with full Boltzmann neutrino transport, systematically changing the treatment of weak interactions, EOSs, and progenitor models. We find that the inconsistent treatment of nuclear abundances between the EOS and weak interaction rates weakens the EOS dependence of both the dynamics and neutrino signals. We also test the validity of two artificial prescriptions for weak interactions of light nuclei and find that both prescriptions affect the dynamics. Furthermore, there are differences in neutrino luminosities by ~10% and in average neutrino energies by 0.25-1 MeV from those of the fiducial model. We also find that the neutronization burst neutrino signal depends on the progenitor more strongly than on the EOS, preventing a detection of this signal from constraining the EOS.
↳ astro-ph.HEnucl-thAstrophys.J.Suppl.(2019)·52 citations
17
Possible bound states with hidden bottom from $K ˉ^{(*)} B^{(*)} B ˉ^{(*)}$ systems
Xiu-Lei Ren🇩🇪 · Zhi-Feng Sun🇨🇳
We study the three-body systems of $K ˉ^{(*)} B^{(*)} B ˉ^{(*)}$ by solving the Faddeev equations in the fixed-center approximation, where the light particle $K ˉ^{(*)}$ interacts with the heavy bound states of $B B ˉ$ ( $B^{*} B ˉ^{*}$ ) forming the clusters. In terms of the very attractive $K ˉ^{*} B$ and $K ˉ^{*} B^{*}$ subsystems, which are constrained by the observed $B_{s 1} (5830)$ and $B_{s 2}^{*} (5840)$ states in experiment, we find two deep bound states, containing the hidden-bottom components, with masses $11002 \pm 63$ MeV and $11078 \pm 57$ MeV in the $K ˉ^{*} B B ˉ$ and $K ˉ^{*} B^{*} B ˉ^{*}$ systems, respectively. The two corresponding states with higher masses of the above systems are also predicted. In addition, using the constrained two-body amplitudes of $K ˉ B^{(*)}$ and $K ˉ B ˉ^{(*)}$ via the hidden gauge symmetry in the heavy-quark sector, we also find two three-body $K ˉ B B ˉ$ and $K ˉ B^{*} B ˉ^{*}$ bound states.
↳ hep-phnucl-thPRD(2019)·13 citations
18
Chiral kinetic theory in curved spacetime
Yu-Chen Liu🇨🇳 · Lan-Lan Gao🇨🇳 · Kazuya Mameda🇨🇳 · Xu-Guang Huang🇨🇳
Many-body systems with chiral fermions exhibit anomalous transport phenomena originated from quantum anomalies. Based on quantum field theory, we derive the kinetic theory for chiral fermions interacting with an external electromagnetic field and a background curved geometry. The resultant framework respects the covariance under the U(1) gauge, local Lorentz, and diffeomorphic transformations. It is particularly useful to study the gravitational or non-inertial effects for chiral systems. As the first application, we study the chiral dynamics in a rotating coordinate and clarify the roles of the Coriolis force and spin-vorticity coupling in generating the chiral vortical effect (CVE). We also show that the CVE is an intrinsic phenomenon of a rotating chiral fluid, and thus independent of observer's frame.
↳ hep-thcond-mat.mes-hallgr-qcnucl-thPRD(2019)·107 citations
19
Spin Polarization and Chiral Condensation in 2+1 flavor Nambu-Jona-Lasinio model at finite temperature and baryon chemical potential
Aman Abhishek🇮🇳 · Arpan Das🇮🇳 · Hiranmaya Mishra🇮🇳 · Ranjita K. Mohapatra🇮🇳
We investigate the ferromagnetic (spin polarization) condensation in (2+1) flavor Nambu Jona-Lasinio(NJL) model with non-zero current quark masses at finite temperature and density which may be relevant in the context of neutron stars. The spin polarization condensation arises due to a tensor type interaction which may be generated due to non-perturbative effects in Quantum Chromodynamics(QCD). In this investigation we have shown the interplay between chiral condensate and spin polarization condensation for different values of tensor coupling. Spin polarization in the case of 2+1 flavor is different from two flavor case because of additional F $_{8}$ condensate associated with $λ_{8}^{f}$ flavor generator. We find a non-zero value of the two spin condensates in the chirally restored phase. Beyond a certain temperature the spin polarization condensates vanish for rather large quark chemical potentials. The spin condensates affect the chiral phase transition, quark masses, and the quark dispersion relation. The spin polarization condensate appears only in the chiral restored phase for light quarks. For large enough tensor couplings, it is observed that the spin polarization condensate acts as a catalyst for chiral symmetry restoration. Thermodynamic behavior of $F_{3}$ and $F_{8}$ are found to be different and they affect the quark masses differently.
↳ hep-phnucl-thPRD(2019)·3 citations
20
Ultrahigh-energy cosmic-ray nuclei and neutrinos from engine-driven supernovae
B. Theodore Zhang🇨🇳 · Kohta Murase🇺🇸
Transrelativistic supernovae (SNe), which are likely driven by central engines via jets or winds, have been among candidate sources of ultrahigh-energy cosmic rays (UHECRs). We investigate acceleration and survival of UHECR nuclei in the external reverse shock scenario. With composition models used in Zhang et al. (2018), we calculate spectra of escaping cosmic rays and secondary neutrinos. If their local rate is $\sim 1$ % of the core-collapse supernova rate, the observed UHECR spectrum and composition can be explained with the total cosmic-ray energy $E_{cr} \sim 1 0^{51}$ erg. The maximum energy of UHECR nuclei can reach $\sim 1 0^{20} - 10^{21} eV$ . The diffuse flux of source neutrinos is predicted to be $\sim 1 0^{- 11} - 1 0^{- 10} GeV cm^{- 2} s^{- 1} sr^{- 1}$ in the 0.1-1 EeV range, satisfying nucleus-survival bounds. The associated cosmogenic neutrino flux is calculated, and shown to be comparable or even higher than the source neutrino flux. These ultrahigh-energy neutrinos can be detected by ultimate detectors such as the Giant Radio Askaryan Neutrino Detector and Probe Of Extreme Multi-Messenger Astrophysics.
↳ astro-ph.HEastro-ph.SRhep-phnucl-thPRD(2019)·44 citations
21
Proton and neutron electromagnetic form factors from lattice QCD
C. Alexandrou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾 · S. Bacchio (Univ. of Cyprus)🇨🇾 · M. Constantinou (Temple Univ.)🇺🇸 · J. Finkenrath (The Cyprus Inst.)🇨🇾 · K. Hadjiyiannakou (The Cyprus Inst.)🇨🇾 · K. Jansen (DESY-Zeuthen)🇩🇪 · G. Koutsou (The Cyprus Inst.)🇨🇾 · A. Vaquero Aviles Casco (Univ. of Utah)🇺🇸
The electromagnetic form factors of the proton and the neutron are computed within lattice QCD using simulations with quarks masses fixed to their physical values. Both connected and disconnected contributions are computed. We analyze two new ensembles of $N_{f} = 2$ and $N_{f} = 2 + 1 + 1$ twisted mass clover-improved fermions and determine the proton and neutron form factors, the electric and magnetic radii, and the magnetic moments. We use several values of the sink-source time separation in the range of 1.0 fm to 1.6 fm to ensure ground state identification. Disconnected contributions are calculated to an unprecedented accuracy at the physical point. Although they constitute a small correction, they are non-negligible and contribute up to 15% for the case of the neutron electric charge radius.
↳ hep-latnucl-exnucl-thPRD(2019)·130 citations
22
The Sea of Quarks and Antiquarks in the Nucleon: a Review
D. F. Geesaman🇺🇸 · P. E. Reimer🇺🇸
The quark and gluon structure of the proton has been under intense experimental and theoretical investigation for five decades. Even for the distributions of the well-studied valence quarks, challenges such as the value of the down quark to up quark ratio at high fractional momenta remain. Much of the sea of quark-antiquark pairs emerges from the splitting of gluons and is well described by perturbative evolution in quantum chromodynamics. However, experiments confirm that there is a non-perturbative component to the sea that is not well understood and hitherto has been difficult to calculate with ab initio non-perturbative methods. This non-perturbative structure shows up, perhaps most directly, in the flavor dependence of the sea antiquark distributions. While some of the general trends can be reproduced by models, there are features of the data that do not seem to be well described. This article discusses the experimental situation, the status of calculations and models, and the directions where these studies will progress in the near future.
↳ nucl-exnucl-thRept.Prog.Phys.(2019)·38 citations

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